Hose clamps can come in a variety of forms, including worm gear hose clamps, T-Bolt, V-Band, and barrel hose clamps. Hose clamps are commonly utilized to join together hoses, tubes, fittings, connectors and other attachments, collectively referred to hereinafter as fittings, for example within the automotive, agricultural, industrial and marine industries.
In use, hose clamps are subjected and respond to a number of ambient and dynamic conditions that effect the clamp assembly. These include thermal cycling between ambient and operating temperatures, vibration, mechanical impingement to the body of the clamp, assembly expansion and contraction, and internal hose and/or fitting system pressures when applicable. These conditions combined with the general rigors of use can cause the clamp's screw, nut, bolt, or the like to loosen, such as by rotating in the direction opposite to that in which it was rotated to install and tighten the clamp. This can cause the clamp to loosen on the fitting, which may result in a loose, weakened connection, and may ultimately result in leakage, mechanical damage, and/or component failure.
In an attempt to prevent such loosening, the screw, nut or bolt may be over-torqued when installed. Over-torqueing of the worm screw, nut, or bolt is not recommended by clamp manufacturers but is often done by clamp installers with the idea that when the screw, nut, or bolt loosens it still retains enough load to prevent the clamp from loosening to a detrimental extent. However, this over-torqueing often causes the clamp to fail. For instance, this can cause the threads of the worm gear screw to deform and even break the mating components in the corresponding band material of the clamp since the clamp is manufactured to accommodate a much lower torque than that actually induced. This over-torqueing also often causes the clamp housing itself to loosen or become detached from the band entirely, which may separate the screw threads from the band causing the clamp to fail. Likewise, in the case of V-Band/T-Bolt clamps, the over torqueing of the nut causes damage to the internal threads of the nut, as well as the mating external threads of the T-bolt, making the nut subject to either seizing in place which prevents further tightening or loosening due to galling of the threads. Similarly, in the case of barrel clamps, this over-torqueing often causes internal damage to the threads of the barrel, as well as to the mating threads of the bolt, making the bolt subject to either seizing in place or loosening due to thread galling. In addition, in many instances over-torqueing of the clamp may crush or degrade the mating fittings due to the generation of excessive radial torque in the fitting/assembly.
As another attempt to reduce loosening of clamp screws, nuts, or bolts has been to use two or more clamps in the same assembly in order to generate greater total load in the mating components. This can also be subject to failure, as radial load is achieved only under each individual clamp, and adding additional clamps to a given assembly doubles, triples, etc. the cost relative to the clamps, while also significantly increasing total assembly time and user burden. Also, using two or more clamps on the same hose, fitting and or assembly is often ineffective to prevent the screw or nut on each clamp from loosening due to the operating characteristics previously described (e.g., thermal cycling).